LFCS Practice Test 3 — 10 Questions

Question 1

A junior administrator needs to create a compressed archive of the /etc directory that preserves file ownership and permissions, and writes it to /backup/etc.tar.gz. Which single command accomplishes this?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

tar -czvf /backup/etc.tar.gz /etc. Creating a gzip-compressed tarball requires the create, gzip, verbose, and file flags together with the source directory. The combination tar -czvf /backup/etc.tar.gz /etc builds the archive in one pass, preserving metadata, and writes it to the specified path. The other commands either attempt extraction, misuse compression tools, or produce non-tar output.

Answer

gzip -r /etc > /backup/etc.tar.gz

Answer

cpio -ov /etc < /backup/etc.tar.gz

Answer

tar -xzvf /backup/etc.tar.gz /etc

Question 2

A user needs to view the contents of a compressed log file /var/log/syslog.gz without first decompressing it. Which command should they use?

Accepted Answer

zcat /var/log/syslog.gz. `zcat` is specifically designed to read the contents of gzip-compressed files without permanently decompressing them. It decompresses the data on the fly and sends the output to stdout, allowing the user to view the log file's contents directly from the terminal.

Answer

gzip -d /var/log/syslog.gz

Answer

gunzip /var/log/syslog.gz

Answer

cat /var/log/syslog.gz

Question 3

You are a system administrator for a company that runs a web server on a Linux system. The web server logs are stored in /var/log/nginx/access.log. The log file grows rapidly and rotates weekly via logrotate. The system has been running for several months. Recently, the development team reported that the web server is responding slowly. You suspect that the disk I/O might be high due to log file activity. You check the disk usage and find that /var/log/nginx/access.log is 4 GB, and the rotated logs (access.log.1.gz, access.log.2.gz, etc.) total another 10 GB. The /var partition has 20 GB total, so it's 70% full. You decide to reduce the disk usage by compressing the current log file and truncating it without stopping the nginx service. Which command sequence should you use to safely achieve this?

Accepted Answer

cp /var/log/nginx/access.log /var/log/nginx/access.log.bak && :> /var/log/nginx/access.log && gzip /var/log/nginx/access.log.bak. It first copies the current log file to a backup, then truncates the original file in place using the shell null command (`:>`) without stopping nginx, and finally compresses the backup. This ensures nginx continues writing to the same inode (file descriptor remains valid) and the disk space is reclaimed after compression.

Answer

:> /var/log/nginx/access.log && cp /var/log/nginx/access.log /var/log/nginx/access.log.bak && gzip /var/log/nginx/access.log.bak

Answer

rm /var/log/nginx/access.log && touch /var/log/nginx/access.log && chmod 644 /var/log/nginx/access.log

Answer

mv /var/log/nginx/access.log /var/log/nginx/access.log.bak && touch /var/log/nginx/access.log && gzip /var/log/nginx/access.log.bak

Question 4

Order the steps to set up a LVM logical volume from a new disk.

Accepted Answer

Create physical volume (pvcreate), then volume group (vgcreate), then logical volume (lvcreate), then format with filesystem (mkfs), then mount.. The correct sequence for setting up an LVM logical volume from a new disk is: first create a physical volume (PV) using pvcreate, then create a volume group (VG) with vgcreate, then create a logical volume (LV) with lvcreate, then format the LV with a filesystem using mkfs, and finally mount it to a directory. This order ensures all dependencies are satisfied: the VG requires the PV, the LV requires the VG, and the filesystem requires the LV.

Answer

Create volume group (vgcreate), then physical volume (pvcreate), then logical volume (lvcreate), then format, then mount.

Answer

Create physical volume (pvcreate), then format (mkfs), then volume group (vgcreate), then logical volume (lvcreate), then mount.

Answer

Create logical volume (lvcreate), then physical volume (pvcreate), then volume group (vgcreate), then format, then mount.

Question 5

An administrator needs to add a new swap space to a running Linux server without rebooting. The server has a free partition /dev/sdc1 and an existing file /swapfile. Which two commands or steps are required to activate the new swap partition /dev/sdc1 immediately? (Choose two.)

Accepted Answer

swapon /dev/sdc1. To activate a new swap partition immediately, you must first initialize it with mkswap, then enable it with swapon. These two commands prepare and activate the swap space without requiring a reboot. Adding an fstab entry is for persistence across reboots, and swapoff or mount are not appropriate for enabling swap.

Answer

swapoff /dev/sdc1

Answer

mount -t swap /dev/sdc1 /mnt

Answer

echo '/dev/sdc1 none swap sw 0 0' >> /etc/fstab

Question 6

A security policy requires that a user's password must expire 90 days after last change, and the user must change it immediately on next login. The last password change was 30 days ago. Which set of commands achieves this?

Accepted Answer

chage -M 90 user1; chage -d 0 user1. `chage -M 90 user1` sets the maximum password age to 90 days, and `chage -d 0 user1` forces the password to expire immediately (setting the last change date to epoch 0), which requires the user to change the password on the next login. This satisfies both requirements: the password will expire 90 days after the forced change, and the user must change it immediately.

Answer

chage -M 90 user1; chage -m 1 user1

Answer

chage -M 90 user1; chage -W 7 user1

Answer

chage -M 90 user1; chage -I 5 user1

Question 7

Refer to the exhibit. The service unit file has Restart=on-failure, but systemctl show displays Restart=no. What is the most likely reason?

Accepted Answer

The unit file was edited but systemctl daemon-reload was not run.. The most likely reason is that the unit file was edited but `systemctl daemon-reload` was not executed. When a service unit file is modified, systemd does not automatically reload the configuration; it continues to use the cached version until `systemctl daemon-reload` is run. This explains why `systemctl show` displays `Restart=no` despite the file containing `Restart=on-failure`.

Answer

The User=backup directive overrides Restart.

Answer

The unit is not enabled.

Answer

The Restart directive is only valid for Type=simple.

Question 8

A service unit has the directive 'ExecStartPre=/bin/true' and 'ExecStart=/usr/bin/myapp'. What is the effect of ExecStartPre?

Accepted Answer

It runs a pre-start script; if it fails, the service is not started.. ExecStartPre is a systemd directive that specifies a command to run before the main ExecStart command. If the ExecStartPre command fails (returns a non-zero exit code), systemd will not proceed to start the service, unless the '-' prefix is used to ignore failure. Here, /bin/true always succeeds (exit code 0), so it does not block the service, but the directive itself is designed to enforce a pre-start check.

Answer

It sets an environment variable.

Answer

It runs a post-start script.

Answer

It runs a pre-start script; if it fails, the service still starts.

Question 9

An administrator is unable to SSH into the server from a remote host at 192.168.1.100. Based on the exhibited iptables rules, what is the most likely reason?

Accepted Answer

The SSH rule only allows connections from 10.0.1.0/24, and 192.168.1.100 is not in that subnet. The exhibited iptables rules show an SSH rule that explicitly accepts incoming TCP traffic on port 22 only from the source subnet 10.0.1.0/24. The remote host at 192.168.1.100 is not within that subnet, so the SSH rule does not match, and the packet will fall through to the next rule or the default policy. Since no other rule permits SSH from 192.168.1.100, the connection is implicitly dropped or rejected, preventing SSH access.

Answer

SSH is not allowed from any source

Answer

The INPUT chain policy is ACCEPT, so SSH should be allowed

Answer

The DROP rule for SSH is not matching because of packet count zero

Question 10

Order the steps to recover a forgotten root password on a Linux system using single-user mode.

Accepted Answer

1. Boot into single-user mode, 2. Remount filesystem as read-write, 3. Change root password, 4. Reboot.. To recover a forgotten root password on Linux using single-user mode, you must first boot into single-user mode (e.g., by adding 'single' to the kernel command line). At the root prompt, the filesystem is mounted read-only, so you must remount it as read-write with 'mount -o remount,rw /'. Then use 'passwd root' to set a new password. Finally, reboot the system. Attempting to change the password without remounting or rebooting prematurely will cause the recovery to fail.

Answer

1. Boot into single-user mode, 2. Change root password, 3. Remount filesystem as read-write, 4. Reboot.

Answer

1. Boot into single-user mode, 2. Remount filesystem as read-write, 3. Reboot, 4. Change root password.

Answer

1. Change root password, 2. Boot into single-user mode, 3. Remount filesystem as read-write, 4. Reboot.